2019 MacBook Pro 16-inch restarts every 3-4 hours

Since you don't really have any third party software installed which is known to cause Kernel Panics, your laptop has a hardware failure with the Logic Board. It is not surprising since this particular model laptop (MBPro 16" 2019) has an extremely high rate of Logic Board failures for multiple reasons....even the replacement Logic Boards Apple installs during the repairs are known to fail (there are multiple reports from users on this forum mentioning the replacement boards failed at first use after the repair & Apple performed another Logic Board replacement).

You can try a DFU Firmware Restore to reset the T2 security chip, system firmware, and internal SSD, but I doubt this will actually help in this case (it is your only possible recourse to try that does not involving money). Unfortunately you will need access to another Mac running macOS 15.7.3+ to perform this procedure and it will destroy all data on that "broken" 2019 laptop. After the procedure, you will need to reinstall macOS through Internet Recovery Mode (the only option available until macOS is reconfigured on the internal SSD).

FYI, I doubt the Apple Diagnostics will reveal any problems. Even the Apple service diagnostics are unlikely to reveal anything either. The diagnostics from Apple have become ever more worthless over the last decade. Plus the only useful diagnostic result is one which actually produces an error condition.

I'm glad to see you have been backing up your laptop. Good job there.

I personally don't recommend spending any money to repair any Intel Macs, but especially not a MBPro 16" (2019) model for multiple reasons. The money spent on repairs is much better put towards a new laptop. The M-series Macs will run circles around this 2019 laptop and will run much cooler as well.

That Mac is suffering from a hardware fault. Contact Apple using the Support link on these pages.

Even after reading countless forums, I have not been able to solve it.

Hardware failure is not something you can solve. It's interesting that none of them pointed that out.

fodor128 wrote:

My 2019 MacBook Pro 16" restarts every 3-4 hours.

I have tried many versions of OS X. It restarts even with a freshly installed OS. I have been struggling with this problem for a year. Even after reading countless forums, I have not been able to solve it.

Run Apple Diagnostics. Perhaps it will reveal the failing hardware component

Use Apple Diagnostics to test your Mac - Apple Support

< Runtime: 30:19 > you would expect a run time of 3 minutes or less for this report

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"

Genius Bar Reservation and Apple Support Options - Apple

Outside the USA

Contact Apple Support - Apple Support

Check Device Coverage

View Coverage - AppleCare & Warranty

I agree with others that data suggests a hardware fault, possibly CPU. However, this one:

Diagnostics Information (past 60 days):

    2026-01-02 06:44:02 Kernel Panic (56 times)

        First occurrence: 2025-12-26 03:42:47

        Details:

            panic(cpu 1 caller 0xfffffff022e8b2a0): userspace watchdog timeout: no

             successful checkins from logd (0 induced crashes) in 180 seconds

            Panicked task 0xffffffe0cd19e9d0: 220 pages, 4 threads: pid 38: watchd

            ogd

can be due to a remote server failing to respond. I see it more in reports from users using OneDrive, but lack enough causative evidence to hang my hat there yet. Still, see if the issue continues if you test with any remote drive access (iCloud; OneDrive; others) turned off.

The ultimate test is to unplug all devices from the computer and perform a Factory Reset and of course, you will want to have a valid backup. This will eliminate a timing fault from an external device causing a Kernel Panic. The OsxFL process seems to be consuming a large amount of resources on your computer and the FL Studio software has been unstable with recent reports. Some Audio plugins have also been a common source of Kernel panics that would cause your Mac to restart.

https://forum.image-line.com/viewtopic.php?t=338143

If the same thing happens on a Clean Install without restore, then you have confirmed a Hardware fault.